Copolymers containing aminoplast units and use thereof as a dispersing agent or stabilizers

ABSTRACT

A description is given of water-soluble aminoplast ether copolymers of the following structural type: 
                         
wherein Z is a glycoluril central unit, B is a radical of an essentially water-insoluble polymer and R1 is a radical of a hydrophilic organic compound. The ratio R1:B is selected within a range of about 1.5 to 4:1 and the overall mass of the water-soluble aminoplast ether copolymer is from about 2000 to 50 000 g/mol such that the copolymer is soluble in water and may be used as a dispersant for e.g. pigments in polar solvents, e.g. water.

BACKGROUND

This application is the U.S. national stage application ofPCT/EP02/14419 (WO 03/055928) with an international filing date of Dec.17, 2002 claiming priority from DE 101 63 985.6 which was filed on Dec.24, 2001.

The invention relates to innovative aminoplast ether copolymers, to aprocess for preparing them and to their use as dispersants orstabilizers.

The aminoplast units normally employed as crosslinking agents in thecuring of paints and varnishes or polymers can be used for linkingchemically different structures. Thus is it possible to preparecorresponding products containing alkyl, ether, ester, amine or urethanegroups.

According to Römpp Lexikon: Lacke and Druckfarben, 1998, Georg ThiemeVerlag, Stuttgart, New York, 148, dispersants are surface-activesubstances which facilitate the dispersing of a pulverulent substance,e.g., a pigment or filler, in a liquid dispersing medium by lowering thesurface tension between the two components. Dispersants facilitate themechanical disruption of agglomerates into primary particles.Additionally dispersants protect the primary particles formed, byforming a protective colloid shell or an electrochemical bilayer,against reagglomeration or flocculation. Where measures againstflocculation or against sedimentation are taken deliberately that leadto steric and/or electrostatic stabilization of the pigment particleswith one another, the term “stabilizers” is used. Stabilized pigmentsexhibit a lesser propensity to settle. In the preparation of paints andvarnishes, dispersants facilitate the incorporation of pigments andfillers, which as important formulating constituents determine thevisual appearance and the physicochemical properties of coatings.Moreover, dispersants may increase the compatibility between chemicallydifferent polymer types.

U.S. Pat. No. 5,629,373 and U.S. Pat. No. 5,914,373 describewater-soluble aminoplast ether copolymers containing polar base polymerunits and polar side chains, which are used as water-soluble associativethickeners.

WO 02/12363 A1 (prior art under Art. 53(2) EPC) describes a special formof the associative thickeners described in U.S. Pat. No. 5,914,373. Theuse of a particular hydrophobicizing compound (tristyrylphenolethoxylate) gives aqueous masonry paints or latex paints a particularstability when tinted with colorant concentrates. The expression“associative thickener” is explained on page 1, last paragraph as:

-   -   “ . . . is recognized in the art to mean a nonionic        hydrophobically modified water-soluble polymer . . . ”

On page 12, line 6 after the formulae it is specified that the mostpreferred hydrophobic attached group is tristyrylphenol. Here as wellthe application is directed very clearly to an aqueous paint. What isdescribed is a special case of the first publication.

The present invention is significantly more advanced in contrast to thetwo aforementioned publications.

A common feature of all the publications is that predominantly linearpolymers can be prepared on the basis of the aminoplast technology. Inthe present case, however, it has been recognized for the first timethat the technique involved is a graft polymer technique which certainlyoffers further possibilities. This is set out also on page 8, para. 1.It is true that the inventive step does not lie in preparing linear,aminoplast-linked chains but rather in the fact that now also the“inverse” forms are claimed, i.e., polymers containing water-insolublebase polymer chains and hydrophilic end groups, which in particular canalso be used in completely polar media. Hybrid forms are likewiseconceivable, with the activity to be achieved generally having nothingto do with the thickening effect (associative linking) but rather with asurface wetting.

Dispersants for pigments and pigment compositions comprising them aredescribed for example in DE 199 04 603 A1, DE 198 36 253 C1, DE 199 05269 A1, WO 97/26984 and EP-A-0 879 860.

In accordance with the state of the art the stabilization of pigmentdispersions and filler dispersions is essentially by steric hindrance insolventborne systems and predominantly electrochemical in aqueoussystems. In aqueous systems in particular it is possible, in the courseof preparation and processing, for numerous problems to occur, which aredescribed in Juan M. Oyarzún, Handbuch der Pigment-verarbeitung,Vincentz-Verlag, 1998:

-   -   difficulty of pigment incorporation, or wetting    -   deterioration in Theological properties    -   sedimentation    -   pigment floating    -   low compatibility with various binders    -   deficient hydrolysis resistance    -   adequate activity only with large amounts added    -   low gloss, low hiding power, inadequate color strength    -   poorly reproducible shades.

Normally use is made of anionic, cationic, nonionic or amphotericdispersants, if desired in polymeric form. In aqueous systems inparticular additives are used that are based on mineral oils,polyacrylates, modified silicones and alkylphenol ethoxylates. Mineraloils, however, lower the gloss and the transparency of the coating andtend toward separation in systems with low levels of pigmentation.Disadvantages of modified natural materials include their low waterresistance and biostability. The polyacrylates that are in theforeground at present in some cases adversely affect the waterresistance, gloss and transparency. The use of alkylphenol ethoxylatesis objectionable from an ecotoxicological standpoint, while silicones insome cases exhibit interadhesion problems and cratering problems(Schmitz et al., Farbe&Lacke, March 2000).

Improvement to the prior art dispersants is also required in respect oftheir universal usefulness, such as, for example, the compatibility withmodern aqueous binder systems (readily miscible, flocculationstability).

It was an object of the present invention to overcome the aforementioneddisadvantages of the prior art and to provide novel dispersants andstabilizers which are easy to prepare and which in aqueous systems inparticular exhibit extremely good performance properties. It is intendedthat a positive influence be exerted on the viscosity stability ofpastes, the color strength and the water resistance of the coatingsprepared therefrom. Additionally the flocculation and aggregation oughtto be avoided. Furthermore, products ought to be used that contain nocosolvents and can be employed universally.

Surprisingly it has been found that the object of dispersing andstabilizing is achieved by means of water-soluble aminoplast ethercopolymers of the following structural type:

where

-   Z is an aminoplast unit based on a glycoluril which is unsubstituted    or substituted by a reactive OR group (where R is an alkyl,    alkylene, alkyl ether or alkyl ester group, preferably a lower alkyl    group, e.g., a methyl or ethyl group);-   B is the radical of an essentially water-insoluble polymer selected    from poly-n-butyl acrylate, poly-n-butyl methacrylate, polyethyl    acrylate, polytetrahydrofuran, polyethyl methacrylate, polymethyl    acrylate, polymethyl methacrylate, a predominantly aliphatic    polycarbonate or a predominantly aromatic polycarbonate, and more    preferably from a poly-n-butyl methacrylate or a predominantly    aliphatic or aromatic polycarbonate having at least two functional    groups which are able to react with the OR function of the    aminoplast unit, preferably having a hydroxyl function;-   R1 is the radical of a hydrophilic organic compound containing at    least one functional group which is able to react with the OR    function of the aminoplast unit to form an ether bond, preferably    having a hydroxyl function, and-   a is at least 1.

The molar ratio R1:B is preferably greater than 1, in particular greaterthan about 1.5 to 4.

According to one particularly preferred embodiment R1 is the radical ofmethylcellulose, polyacrylic acid, polymethacrylic acid,ethylene/acrylic acid/sodium acrylate copolymer, polyalkylglycol,polyvinyl alcohols or polyvinylpyrrolidone, preferably the radical of amethoxy-terminated polyalkylglycol.

Preferably at least one side chain R1 is water-soluble and connected viaan ether bridge to the central unit Z.

More preferably B is hydrophobic and/or R1 is hydrophilic.

The index a can be from 1 to 1000. In general the average molar mass ofdispersants is from 1000 to 100 000, preferably from 2000 to 50 000,more preferably from 2500 to 40 000. The copolymers of the invention arepreferably predominantly linear.

R1 (side chains of the copolymer) preferably has an average molar massof from about 500 to 30 000 g/mol, in particular from about 1000 to 20000 g/mol, more preferably from about 1500 to 10 000 g/mol.

B preferably has a molar mass of from about 100 to 30 000 g/mol, inparticular from about 200 to 20 000 g/mol, more preferably from about300 to 10 000 g/mol.

Additionally the overall molar mass of the aminoplast ether copolymersof the invention is preferably between about 1000 and 100 000 g/mol, inparticular between about 2000 and 50 000 g/mol, more preferably betweenabout 2500 and 40 000 g/mol.

The molar ratio B:Z is preferably between about 0.5:1 and 4:1. The molarratio Z:R1 is preferably between about 1:0.25 and 1:5. The molar ratioR1:B is greater than 1 and is preferably about 1.5 to 4:1.

Examples of graft copolymers of the invention are depicted in FIGS. 2.1to 2.3.

The copolymers of the invention can be prepared by known methods, e.g.,in accordance with U.S. Pat. No. 5,914,373 in from 10% to 60% strengthsolution of an alkylated benzene (toluene or xylene). In general theaminoplast unit Z is reacted with the organic compounds from which theradicals B and R are derived, and/or with prepolymers formed therefrom,under acidic catalysis in solution or without solvents, preferablyemploying a one-pot method.

The preparation of similar aminoplast systems is also described inDE-A-100 38 147 in U.S. Pat. No. 5,627,232 as well, the content of whichis hereby expressly incorporated by reference into the presentdescription, the polyfunctional aminoplast units Z reacting under acidcatalysis with monofunctional and polyfunctional organic compounds (R1and B).

Surprisingly it has been found that the desired copolymers can beprepared in analogous manner by means of a one-pot reaction. For thatpurpose the reactants in from 15% to 35% strength solution in respect ofmonomers used (total reactants), in particular in from 20% to 30%strength solution, are reacted at temperatures from about 60 to 140° C.,preferably from about 70 to 130° C., in solution or without solvent (inbulk). In general residues of water are removed with an inert solvent,such as toluene or xylene, for example, or by applying reduced pressure.In order to remove the low molecular mass condensation product formedduring the reaction more easily (e.g., methanol, butanol), it isadvisable to add an inert solvent, such as toluene, xylene or apetroleum fraction, or else to evacuate. As initiator it is usual to addacids, e.g., sulfonic acids. The optimum amount for addition is betweenabout 0.2% and 10% by weight, preferably between about 0.2% and 7.0% byweight, based on the sum of the functional monomers. The reaction iscarried out under reduced pressure, and when working with solvent thesolvent removed by azeotropic distillation is continually replaced withfresh solvent.

According to one preferred embodiment a neutralizing agent, an amine forexample, is added after a reaction time of from about 2 to 10 h,preferably from about 2.5 to 8 h, to give molar masses of the copolymersof from about 2000 to 50 000 g/mol, more preferably from about 2500 to40 000 g/mol.

The progress of the reaction can be ascertained by determining theviscosity or by determining the amount of low molecular masscondensation product. The products of the reaction are liquid orthermoplastic and water-soluble.

One further aspect of the present invention relates to the provision ofdispersants and stabilizers for pigments or fillers. Thus it hassurprisingly been found that for this purpose the aminoplast ethercopolymers of the invention in which Z is a glycoluril and B, R1 and aare as defined above exhibit unexpectedly good properties. Theaminoplast ether copolymers of the invention used with preference arewater-soluble and can be employed with particular advantage in aqueoussystems.

Additionally it has surprisingly been found that the water-soluble graftpolymers or graft copolymers of the somewhat more general formula belowalso constitute advantageous dispersants and stabilizers for pigments orfillers:

in which (B_(a)) to (B_(b)) are predominantly apolar base polymer chainswhich are identical or different from one another and which optionallyhave free valences for the formation of a crosslinked structure; Z_(x)to Z_(z) are central units which are identical or different from oneanother and which optionally have free valences for the formation of acrosslinked structure; (S₁) to (S₄) are polar or apolar side chainswhich are identical or different from one another; m=1 to 100,preferably 2 to 50, in particular 2 to 20, and n is an integer from 0 to500, preferably 1 to 100, in particular 1 to 50, and the structure iscompleted by polar end groups.

Graft polymers and/or graft copolymers of this kind are also describedin DE-A-100 38 147, the disclosure content of which in this respect isalso adopted into the present description by express reference.

It is has surprisingly been found that particularly good dispersants, inparticular for aqueous systems, are obtained if m is 11 to 100, inparticular 12 to 50 and more preferably 12 to 20.

The main chain of the graft polymer or copolymer is essentially a linearmolecule. This molecule is produced by subjecting at least onedifunctional molecule to addition polymerization or polycondensation,e.g., a diisocyanate, a diester, a dicarboxylic acid, a dicarboxylicanhydride, a diol, a lactone, a lactam, or another difunctional compoundfrom the group of the silanes or siloxanes.

In the simplest case the “side chains” are the different terminal groups(terminating end groups). In the case of graft polymers or copolymershaving a very high molecular weight, however, modification via the endgroups is not enough to effect substantial change in the molecularproperties of these products. Such change can be expected only atrelatively low molecular weights, from 10 000 to 100 000 g/mol, forexample. In the case of higher molecular mass graft polymers orcopolymers it is necessary to insert functional groups.

The graft polymers or copolymers can be prepared conventionally, e.g.,in solvents, in water or by direct reaction of the “building blocks”with or without the aid of a catalyst.

Appropriate selection of the side chains enables the resulting HLB(hydrophilic/lipophilic balance) to be tailored. If the medium for whichthe innovative graft copolymer is prepared is predominantly hydrophilicthen the base polymer will likewise be selected from the class ofpredominantly hydrophilic polymers (e.g., polyethylene glycol (PEG) inExample B of U.S. Pat. No. 5,627,232.

If, however, the field of use is an entirely apolar medium, such as apolyethylene or polypropylene, for example, then a predominantly apolarbase polymer is used, e.g., a long-chain and terminal diol or apolyethylene wax containing terminal OH groups.

For partly hydrophilic and hydrophobic systems it is also possible touse a correspondingly adapted base polymer based on polyethylene glycol,propylene glycol, polytetrahydrofuran or combinations and/or blockpolymers thereof, the corresponding polarities being introduced by wayof the base polymer.

The aminoplast central unit is preferably composed of monomers of theformulae

in which R is a lower alkyl group, preferably a methyl or ethyl group.

The base polymer chain (B_(a)) to (B_(c)) is preferably a polyalkylenemoiety, e.g., a polyethylene or polypropylene moiety; a polyoxyalkylenemoiety, e.g., a polyoxyethylene or a polyoxy(ethylene-butylene) moiety;a polyurethane moiety, a polyoxyacrylate or polyoxymethacrylate moiety,a polycarbonate moiety and/or a polysiloxane moiety.

In the graft polymers or copolymers of the invention the side groups(S₁) to (S₃) can be selected from hydrophobic and/or hydrophilic sidegroups, particularly from unilaterally alkyl-terminatedpolyethylene/polypropylene copolymers, saturated or unsaturated C₉-C₃₆alkyl ethoxylates, CH₃—O—[CH₂—CH₂—O—]_(p)H, alk-O—[CH(CH₃)CH₂O—]_(p)H,or CH₃—(CH₂)nCH═CH—(CH₂)m-CH₂OH (n, m, p=1 to 500). These side groupscan also be used as R1.

Preferably in the graft polymers or copolymers n is an integer from 1 to500, in particular from 1 to 100, e.g., from 1 to 50.

In the graft polymers or copolymers of the invention the base polymerchains (B_(a)) to (B_(b)) can be substantially polar and the side chains(S₁) to (S₄) substantially apolar, or vice versa. Additionally the graftpolymers or copolymers of the invention can be in solid or liquid formand can have the molar mass indicated above for the aminoplast ethercopolymers of the invention.

The aminoplast-based copolymers of the invention are surprisingly highlysuitable, as mentioned above, as dispersants and/or stabilizers forpigments and/or fillers, and also in particular for preparing pigmentconcentrates for aqueous systems. In this context the dispersant and/orstabilizer is homogenized together with the pigments and/or fillers tobe dispersed, optionally in the presence of organic solvents and/orwater, optionally with binders and optionally with customary coatingsauxiliaries. The above-described copolymers may also be used forpreparing a coating composition, in which case a binder, optionally asolvent, pigments and/or fillers, the copolymer and optionallyauxiliaries are dispersed together. The copolymers of the inventionaccording to claim 1 provide an innovative class of dispersants havingunexpectedly good properties for aqueous systems.

For the preparation of aqueous pigment pastes according to one preferredembodiment from 0.1% to 100% by weight of the copolymers of theinvention, preferably from 0.2% to 80% by weight (based on the weight ofthe pigments) are added. This, however, is dependent on the surface areato be covered on the solid to be covered. Carbon black requires verymuch more dispersant than, for example, TiO₂. The dispersants aregenerally applied to the solids in the presence of solvents and/orwater. Alternatively they may be applied directly to the solids that areto be dispersed. For that purpose the copolymers can be mixed with thepigments to be dispersed or dissolved directly the dispersing medium(water, optionally additions of glycol ether) prior to or simultaneouswith the addition of the pigments and, where used, other solids.

The dispersants or stabilizers of the invention are particularlysuitable for preparing pigment concentrates. Aqueous, highlyconcentrated, pumpable and flowable pigment preparations can be preparedin a simple way by dissolving the copolymer of the invention in water,together if desired with a further component, adding the pigment withstirring, and dispersing the mixture until the desired fineness andconsistency is achieved. Another method consists in mixing a pigment orfiller with the copolymer of the invention; the mixture can be dispersedin water if necessary. Furthermore, an aqueously moist pigmentfiltercake can be admixed with the copolymer of the invention andincorporated into the pigment filtercake using a dissolver, for example.

The dispersants or stabilizers of the invention can be used for anydesired pigments and fillers. Examples of pigments to be dispersed arefamiliar to the skilled worker and are disclosed for example in DE-A-19904 603 on pages 6 and 7, hereby explicitly incorporated by reference.The solids (fillers) to be dispersed for which the copolymers of theinvention can be used include—without being restricted to—the organicand inorganic pigments that are known to the skilled worker, which canbe found both in Pigment Handbook, Vols. 1-3, John Wiley & Sons, NewYork, 1988 and in Ullmann's Encyclopedia of Industrial Chemistry, Volume5, Vol. 20.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is now illustrated with reference to the following,non-limiting examples; in the drawings

FIG. 1 shows examples of aminoplast central units (Z), corresponding tothe more general definition of claim 20;

FIGS. 2.1 to 2.3 show preferred copolymers according to the invention,where b, c, d and e are any integer, preferably from 1 to 100, inparticular from 1 to 50, and e is preferably defined like a (cf. above)b, c, d and e can also be 0 if at least one of them is 1.

PREPARATION EXAMPLES Example 1 (in Solution)

A reaction vessel is charged with 17 g of polytetrahydrofuran having amolar mass of 2900 (PolyTHF 2900; BASF), 3.73 g of glycoluril(Powderlink® 1174; Cytec), 87.93 g of monomethoxyethylene glycol with amolar mass of 5000 and 400 ml of toluene, this initial charge is heatedto 135° C. under nitrogen and traces of moisture are removed byazeotropic distillation. After 1 hour the reaction is initiated byadding 0.48 g of Nacure 5076 (70% dodecylbenzenesulfonic acid inisopropanol, Worlee) under a vacuum of 530 mbar and continuous dropwiseaddition of fresh toluene. The course of the reaction can be monitoredby gas chromatography analysis of the distillate for the amount ofmethanol it contains. After a reaction time of approximately 5 hours theconversion is quantitative and the reaction is halted by adding 0.31 gof triethanolamine (Acros). Reaction is allowed to continue for 10minutes under nitrogen, the clear, viscous solution is poured into traysand the product is dried to constant mass in a vacuum drying oven at 60°C. Analysis of the polymer obtained by gel chromatography indicates anM_(n) value of 19 100 (calibration against polystyrene/THF) with anM_(n)/M_(w) ratio of 1.42. Evaluation of the peak area of the monomerindicated a residual monomer content of 10%.

Example 2 (in Bulk)

A sigma mixer is charged with 1700 g of polytetrahydrofuran (PolyTHF2900; BASF), 373 g of Powderlink® 1174; Cytec) and 8793 g of polyglycolM 5000 S (Clariant). The reactants are dried at 105° C. and a vacuum of40 mbar with stirring at 30 rpm for about 3 hours until gas is no longerevolved. The vacuum is broken with nitrogen and the reaction isinitiated by adding 48 g of Nacure® 5076 (70% dodecylbenzenesulfonicacid in isopropanol, Worlee). Kneading is carried out under vacuum at 30rpm. After a reaction time of approximately 1.5 hours the reactionmixture becomes highly viscous. By adding 31 g of triethanolamine(Acros) and 1 g of 2,6-di-tert-butyl-4-methylphenol (antioxidant) thereaction is halted under nitrogen. The product is waxlike and soluble inwater. The reaction time is important for the product properties, withreaction times of from about 2 to 10 hours, in particular from 2.5 to 8hours, being preferred for products having molar masses of from 2500 to40 000.

Examples 3 to 14

Further copolymers were prepared in accordance with Example 1, varyingthe stoichiometry and the chemical structure of the bifunctional ormonofunctional organic compounds. The individual compositions arespecified in Table I, the abbreviations used being as follows:

-   THF: Polytetrahydrofuran-   BA: Poly-n-butyl acrylate diol-   MMA: Polymethyl methacrylate diol-   PC: Polycarbonate diol-   PPG: Polypropylene glycol-   PEG: Polyethylene glycol-   MPEG: Monomethoxypolyethylene glycol with a molar mass of 5000-   MPEG2: Monomethoxypolyethylene glycol with a molar mass of 2000-   HEEU: Hydroxyethylethyleneurethane-   DMP: Dimethoxypropionic acid

TABLE I Organic Organic Powderlink compound B compound R1 1174 InitiatorExample [mol] [mol] [mol] [mol] 1 THF 0.006 MPEG 0.018 0.012 0.0015 2 BA0.010 MPEG 0.030 0.020 0.003 3 MMA 0.010 MPEG 0.030 0.020 0.003 4 PC0.006 MPEG 0.018 0.012 0.002 5 PPG 0.015 MPEG 0.023 0.030 0.007 HEEU0.023 6 PEG 0.015 MPEG 0.023 0.030 0.007 HEEU 0.023 7 THF 0.014 MPEG20.041 0.028 0.0012 8 BA 0.010 MPEG 0.030 0.020 0.0014 9 MMA 0.023 MPEG0.070 0.043 0.007 10 PC 0.015 MPEG 0.045 0.030 0.003 11 PPG 0.015 MPEG 20.023 0.030 0.004 HEEU 0.023 12 BA 0.020 MPEG 0.020 0.020 0.0024 13 PC0.020 MPEG 0.020 0.020 0.0024 14 BA 0.020 MPEG 2 0.060 0.080 0.0030 DMP0.020The reaction time is between about 2 and about 7 hours.

Use Examples Example 15 (Pigment Paste)

To assess the compounds of the invention pigment concentrates wereprepared without additional binder and an evaluation was made of theirviscosity, which is a measure of the dispersibility of a solid. Toprepare the pigment pastes the copolymers of the invention (ex. 1 to 4)are initially dissolved at 20% strength in water, the solutions aremixed with water and auxiliaries and the pigments are added. Dispersingtakes place following the addition of grinding media (70 g of glassbeads of 2 to 3 mm) in a dispersing apparatus (Dispermat) with a singleTeflon disc at 8000 rpm for 20 minutes with water cooling. This givesflowable pigment pastes, which were added to a white paint (acrylicpaint, Akzo-Nobel). The test formulations were drawn down and assessedby the rub-out test. Additionally the compatibility of the compounds ofthe invention with binders was tested. For that purpose 5% of additive(examples 1 to 14 of Table I; 20% strength in water) were stirred intothe binder dispersion using a Pendraulik stirrer (type LD50) withtoothed dissolver disc (level 1-2), and the resulting systems wereapplied and inspected.

The viscosity of the pigment pastes was measured using the Bohlin CSviscometer (Bohlin Instruments); colorimetry was carried out with theTCS instrument from BYK Gardner. The comparative additive used wasDisperbyk 190 (BYK Chemie).

Formulation of the White Paste (Amounts in Parts by Weight)

70.0 titanium dioxide 2310 (Kronos) 8.8 additive solution, 40% strength1.0 defoamer (BYK 0.24; BYK-Chemie) 15.8 waterFormulation of the Blue Paste (Amounts in Parts by Weight)

29.2 Heliogen Blue L 7072 D (BASF) 29.2 additive solution, 40% strengthor 58.4 additive solution, 20% strength 0.8 defoamer (e.g., BYK 024, BYKChemie) 0.3 preservative (e.g., Acticide SPX, Thor) 40.5 or 11.3 waterFormulation of the Iron Oxide Paste (Amounts in Parts by Weight)

60.0 iron oxide (Bayferrox 130 M; Bayer AG) 10.5 additive solution (40%strength) 1.0 defoamer 28.5 waterTest Paint

Ready-mixed white paint (acrylic paint, Akzo-Nobel)

Results

TABLE II Paste viscosity (mPa) at rotational speed D [s⁻¹] D = 100Pigment Example D = 10 [s⁻¹] [s⁻¹] D = 1000 [s⁻¹] Kronos 2310Comparative 426 191 98 24 h or 4 2 810 416 161 weeks 4 1629 850 344 81007 551 151 12  532 204 102 Heliogen Comparative 726 189 64 Blue L70722 397 255 154 D after 4 979 486 204 24 h 8 50 42 35 12  2998 892 293Heliogen Comparative 542 156 69 Blue L7072 2 332 218 139 D after 4 4 781403 205 weeks/40° C. 8 sediment — — 12  2376 771 273 Iron oxideComparative 617 145 48 Bayferrox 2 2195 411 97 130 M after 48 941 370144 24 h 8 1657 267 130 14  1132 366 181 Bayferrox Comparative 710 130 Mafter 4 2 sediment 177 62 weeks/40° C. 4 3521 8 sediment 584 123 14 1443 528 185 2003 374 144 1200 388 185

TABLE III Colorimetry of the pigment concentrate/white paint blend 1/99Delta E after Example Lightness L* rub-out* Heliogen Blue Comparative80.2 9.6 L7072 D 2 79.3 8.3 (which 24 h 4 76.7 0.5 or 4 weeks?) 8 78.85.3 14  79.3 7.6 Bayferrox Comparative 66.5 1.07 130M 2 65.7 1.02 4 66.30.58 8 65.3 0.42 14  66.2 1.13 *determined using the TCS colorimeterfrom BYK-Gardner

TABLE IV Compatibility with binder (5% dispersant, based on binder) PVAPU AC SA (Mowolith (Alberdingk (Neocryl (Acronal S Example LDM1871) U610) XK-90) 559) Comparative moderate good good moderate 2 good goodgood good 4 good good good good 8 moderate good good moderate 12  goodgood good good

All of the dispersants investigated in Table IV are highly compatiblewith the binders investigated and do not show any adverse effects ongloss, drying or water resistance.

1. Water-soluble aminoplast ether copolymers of the following structuraltype:

where: Z comprises an aminoplast unit based on a glycolurile of formula

wherein R is selected from the group consisting of hydrogen, alkylgroups, and acyl groups; B comprises a radical of an essentiallywater-insoluble polymer selected from poly-n-butyl acrylate,poly-n-butyl methacrylate, polyethyl acrylate, polytetrahydrofuran,polyethyl methacrylate, polymethyl acrylate, polymethyl methacrylate, apredominantly aliphatic polycarbonate and a predominantly aromaticpolycarbonate, which are able to react with the OR-function of theaminoplast unit, R1 comprises a radical of a hydrophilic organiccompound containing at least one functional group which is able to reactwith the OR group of the aminoplast unit to form an ether bond, selectedfrom the group consisting of a radical of methylcellulose, polyacrylicacid, polymethacrylic acid, ethylene/acrylic acid/sodium acrylatecopolymer, polyalkylglycol, polyvinyl alcohols and polyvinylpyrrolidone,and a is at least 1; wherein the overall mass of the water-solubleaminoplast ether copolymer is from about 2000 to 50 000 g/mol. 2.Aminoplast ether copolymers of claim 1 wherein R is selected from thegroup consisting of alkyl groups having 1 to about 4 carbon atoms, andacyl groups having 1 to about 4 carbon atoms.
 3. Aminoplast ethercopolymers of claim 1 wherein R is selected from the group consisting ofmethyl and ethyl groups.
 4. Aminoplast ether copolymers of claim 1wherein the R1 radical has a molar mass of from about 500 to 30 000g/mol.
 5. Aminoplast ether copolymers of claim 1 wherein the B radicalhas a molar mass of from about 100 to 30 000 g/mol.
 6. A process forpreparing an aminoplast ether copolymer of claim 1 comprising reactingthe aminoplast unit Z with B and R1 radicals or with prepolymers formedtherefrom under acidic catalysts in solution.
 7. The process accordingto claim 6, wherein the reaction is carried out in a one-pot process infrom 15% to 35% strength solution in respect of total reactants used at70 to 130°C., and, after reacting for about 2 to 10 h, adding aneutralizing agent, to obtain molar masses of the copolymers of fromabout 2000 to 50 000 g/mol.
 8. An Aminoplast ether copolymers obtainedby the process of claim
 6. 9. A dispersant or stabilizer for pigments orfillers comprising the aminoplast ether copolymers of claim
 1. 10. Thedispersant or stabilizer of claim 9 mixed in an aqueous system.
 11. Acoating composition, comprising a binder, pigments and/or fillers, andthe aminoplast ether copolymer of claim 1 dispersed together.
 12. Apigment paste comprising a pigment, a solvent and the aminoplast ethercopolymer of claim
 1. 13. The aminoplast ether copolymers of claim 1wherein the essentially water-insoluble polymer B comprises a hydroxylfunction.